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Biomedical subjects

Klaus Louis Gerlach

Publications and source records attributed to Klaus Louis Gerlach.

6 recordsLinked to original sources
PubMed2006

Open versus closed treatment of fractures of the mandibular condylar process-a prospective randomized multi-centre study.

AIM: The aim of this international prospective randomized multi-centre study was to compare operative and conservative treatment of displaced condylar fractures of the mandible. METHODS AND PATIENTS: Out of a total of 88 randomized patients from 7 centres, 66 patients with 79 fractures of the mandibular condylar process completed the study and were evaluated. All fractures were displaced, being either angulated between 10 degrees and 45 degrees or the ascending ramus was shortened by more than 2mm. The follow-up examinations 6 weeks and 6 months following treatment included evaluation of radiographic measurements, clinical, functional and subjective parameters including visual analogue scale for pain and the Mandibular Function Impairment Questionnaire index for dysfunction. RESULTS: Correct anatomical position of the fragments was achieved significantly more often in the operative group in contrast to the closed treatment group. Regarding mouth opening/lateral excursion/protrusion, significant (p=0.01) differences were observed between both groups (open 47/16/7mm versus closed 41/13/5mm). The visual analogue scoring revealed significant (p=0.03) differences with less pain in the operative treatment group (2.9 open versus 13.5 closed). The Mandibular Function Impairment Questionnaire index recorded a significant (p=0.001) difference with less pain and discomfort in the open treatment group (10.5 versus 2.4 points). CONCLUSION: Both treatment options for condylar fractures of the mandible yielded acceptable results. However, operative treatment, irrespective of the method of internal fixation used, was superior in all objective and subjective functional parameters.

Adult↗
PubMed2006

Resorbable poly(D,L)lactide plates and screws for osteosynthesis of condylar neck fractures in sheep.

We made osteotomies in the condylar neck in 12 adult sheep to simulate fractures, and joined the two ends with 2 poly(D,L)lactide (PDLLA) plates and 8 PDLLA screws 2mm in diameter. The animals were killed after 2, 6, and 12 months and bony healing was assessed macroscopically and histologically. The plates and screws remained intact and there was no displacement of the bony ends. The degrading plates, which were still visible in the specimens after 6 months, had been replaced by bone. At 12 months the PDLLA had been resorbed with no foreign body reaction and no resorption of underlying bone. The articular discs showed no signs of degeneration.

Absorbable Implants↗
PubMed2003

Transversal palatal expansion using a palatal distractor.

METHOD AND RESULTS: The method and first results of transversal expansion with a palatal distractor in adolescents and adults with transverse maxillary deficiencies are presented. In ten patients with a mean age of 25.8 years, a newly developed distractor was applied for bone-borne expansion of the two halves of the maxilla following osteotomy of the lateral walls of the maxillary sinuses and the midpalatal suture. After a 3-week distraction period, mean changes of 8.8 mm in intercanine distance (ICD), 8.6 mm in anterior dental arch width (ADA), and 8.3 mm in posterior dental arch width (PDA) were registered. 6 months after the subsequent multibracket appliance therapy, these values were found to be largely constant. CONCLUSION: Because of the short treatment period, the absence of relapses, and the handling simplicity for the patient, this method is recommended for clinical application.

Adolescent↗
PubMed2002

pH-stabilization of predegraded PDLLA by an admixture of water-soluble sodiumhydrogenphosphate--results of an in vitro- and in vivo-study.

Aim of the study was to examine if the addition of buffering sodiumhydrogenphosphate to poly(D,L)lactide(PDLLA) would stabilize the pH-value in the in vivo environment of implanted material and whether this improves its biocompatibility. The material was predegraded just to the point of viscous disintegration to test the PDLLA in the moment of its most aggressive effect on the surrounding tissue. Racemic amorphous PDLLA was injection-molded with or without the admixture of 1 mol NaP per 100 mol lactate, the degradation product of PDLLA (=1 mol%) to form 20mm x 3 mm x 2mm rods. Predegradation was performed by storing the rods at 55 degrees C for 14 days, just to the point of beginning dissolution. Predegraded PDLLA or PDLLA + NaP samples were used for in vitro incubation tests, as well as for the in vivo study, where the rods were implanted into the spinal muscles of 30 male Wistar rats. Repeatedly, measurements of the pH-value were made in the incubation solutions in vitro. The surrounding tissue of the implanted samples as well as the normal contralateral muscle tissue was checked for its pH-value in a group of 3 rats, respectively, anaesthesized at various time intervals after implantation. After these measurements the implants and their surrounding tissues were excised for histological examination. In Ringer's solution pH-values dropped immediately within the first week of incubation of both predegraded materials reaching -4 pH units after 4 weeks in the PDLLA containing medium, after 6 weeks in the PDLLA + NaP containing medium. Soerensen buffer slowed the pH decrease with significant differences between the material groups up to the 28th week. In vivo, the pH of the surrounding tissue was influenced by the implanted PDLLA material up to the 4th week, while the admixture of NaP resulted in a significant pH stabilization. A higher quantity of macrophages and giant cells were seen between the 2nd and 6th week after the implantation in the environment of pure PDLLA compared with PDLLA + NaP. Complete resorption of predegraded pure PDLLA or PDLLA + NaP from the extracellular space was reached 28 weeks postimplantation in vivo. Thus, sodiumhydrogenphosphate improves the biocompatibility of degrading PDLLA at the point of viscous disintegration by stabilizing the pH-value in the environment of the implants for several weeks and reducing adverse tissue reactions.

Animals↗
PubMed2001

Analysis of the osseous/metal interface of drill free screws and self-tapping screws.

Aim: A comparison of metal/osseous interface and bone remodelling after insertion of different types of titanium bone screws in vivo. Material: Samples of five of each of the following bone screw types were inserted into the anterior wall of the frontal sinus of five Göttingen minipigs: self-tapping micro- (1.5 mm) and miniscrews (2.0 mm) or drill free micro- (1.5 mm) and miniscrews (2.0 mm) (Martin Medizintechnik, Tuttlingen, Germany). Screw length was 7 mm. Methods: Sequential intraperitoneal injections of fluorochromes were performed between the second and ninth postoperative week. After 6 months the pigs were sacrificed, the screw-bone-blocks resected, and microradiographic, histological and fluorescence microscopical examinations were carried out. Results: Using drill free screws, mean screw/bone contact was 88.4% (miniscrews), or 93.8% (microscrews). With self-tapping miniscrews it was 54.9%, but in microscrews 81%; the differences were statistically significant (t -test: p<0.05). By fluorescence microscopy, the amount of bone remodelling (ratio of residual vs. newly formed bone) was measured. Significantly more of the residual bone was found in the region of the screw threads using drill free screws (miniscrews: mean 71.8%, microscrews: mean 67.9%) than in the region of screw threads with self-tapping screws (miniscrews: mean 33.1%, microscrews: mean 42.4%). Conclusion: The present data support the view that screw/bone contact with drill free screws was superior to that of self-tapping screws; the greater amount of original bone in the threads of drill free screws demonstrated that the insertion of drill free screws did not cause harm to the surrounding bone. Both results are important for osteosynthesis in regions where thin cortical bone is present, such as the central midface. Copyright 2001 European Association for Cranio-Maxillofacial Surgery.

Journal Article↗